Chain substitution caused sub-fibril level differences in electromechanical structure and property of wild-type and oim/oim collagen fibers

Electromechanical changes in type I collagen caused by diseases are pivotal for monitoring bone health and offering informative message of constructing biobased smart devices. Here, we employ a mouse model of osteogenesis imperfecta (oim/oim), which is genetically modified through mutating the α-2 chain to α-1 chain in the collagen fibrils of the wild-type model (+/+ or heterotrimer), resulting in three α-1 chains in the collagen fibrils (i.e., homotrimer). Piezoresponse force microscopy (PFM) is used to directly visualize the sub-micrometer structures and piezoresponses of +/+ and oim/oim collagen fibers. Results show that the compact and highly ordered +/+ collagen fibers possess larger in-plane piezoresponses than the loosely packed and randomly distributed oim/oim collagen fibers. The mean values of the lateral PFM amplitude are 108.53 pm and 77.72 pm with interquartile ranges of 98.56–117.47 pm and 71.21–85.93 pm for +/+ and oim/oim collagen fibers, respectively. Molecular simulations demonstrate that the structural stability and electrically induced activity of heterotrimer are better than those of homotrimer, suggesting better biopiezoelectricity of comprising diverse polar residues (atomic charges) within the oriented heterotrimeric collagen molecular structure. Our study provides a new insight into the functional changes of human osteogenesis imperfecta.